Method and apparatus for treating an underground formation



Jan. 2, 1968 e. c. HOWARD ET AL 3,361,204

METHOD AND APPARATUS FOR TREATING AN UNDERGROUND FORMATION 2 Sheets-Sheet 1 WILLIAM G. BEARDEN GEORGE C. HOWARD INVENTORS.

Filed Jun 25, 1965 ATTORNE Y.

Jan. 2, 1968 G. c. HOWARD ET AL 3,361,204

METHOD AND APPARATUS FOR TREATING AN UNDERGROUND FORMATION 2 Sheets-Sheet 2 Filed June 25, 1965 FIG. 4

ATTORNEY.

United States Patent 3,361,204 METHOD AND APPARATUS FOR TREATING AN UNDERGROUND FORMATION George C. Howard and William G. Bearden, Tulsa, Okla, assignors to Pan American Petroleum Corporation, Tulsa, Okla, a corporation of Delaware Filed June 25, 1965, Ser. No. 467,041 5 Claims. (Cl. 166-35) ABSTRACT OF THE DISCLOSURE Apparatus and method for use in treating a formation penetrated by a well bore. Means are provided whereby an annular portion of the well bore adjacent the formation to be treated is isolated. A tubular member having a window is suspended at the lower end of a string of tubing adjacent the isolated annulus. A perforating gun is lowered through the tubing string until it is in the tubular member. Orienting means are provided to orient the gun in relation to the window in the tubular member. The gun is then fired with the bullet penetrating the casing and the formation. Treating fluid is then injected through the tubing in the isolated space so that it passes through the perforation just made and on into the formation.

This invention relates to an apparatus and method for use in treating a formation penetrated by a well bore. It relates especially to a tool which can be used in a well bore and through which a treating agent is injected such as into an unconsolidated underground formation to bond the loose particles together.

Many oil and gas wells produce from incompetent or unconsolidated formations. By this it is meant that the sand particles are not strongly bound together and that as fluid moves from such formations into the well, the smaller particles of sand, clay and the like are carried into the well. The removal of these particles from the formation enables other larger particles to shift their positions. In some instances, these larger particles are also carried into the well. The moving of such larger particles removes support for additional smaller particles so that they too migrate toward the well. The matter of sand production can become a very serious problem. In some instances the sand particles cause mechanical damage to the well completion equipment to the extent that it must be replaced. This, of course, is costly. However, sometimes the damage is even more costly. In some severe cases where an excessively large amount of the formation has been removed, the damage is so great that the well casing itself is sometimes damaged or collapsed to the point where the well must be abandoned.

Many means have been suggested for relieving this sand production problem. For example, gravel packs are sometimes placed opposite unconsolidated zones to filter the solids out of the fluids moving toward the well. Various agents have also been used to consolidate the sand and other loose particles in place into a rigid mass to prevent this movement. One method of injecting treating agents into the formations to be consolidated is described in Patent No. 3,189,091 issued June 15, 1965. That patent describes one particularly desirable Way of consolidating a formation. In a preferred method in that patent a pliant or elastic material, such as an aromatic polyisocyanate, is deposited on the particles in the formation whereby they are cemented together in a soft or rubbery mass. The cementing material used is one which is activated and caused to deposit by Water in the formation. In that method, the cementing material is injected into the formation in a solution with a solvent which is miscible with both water and the organic petroleum residue near the well. The product produced by the water activating the material is insoluble in the formation fluids and is preferably pliant. When the particles are cemented together with an elastic material, the formation yields a slight amount and fluid flows therethrough without releasing particles.

In some cases, one of the problems with treating an unconsolidated formation with a consolidating agent is the proper placing of that agent. That portion of the formation immediately surrounding the well bore to which fluid is to be produced, e.g. all of the formation within 1 or 2 feet of the perforation through which formation fluid is produced, should all be contacted with the treating agent. If some of such portion of the formation is not thus contacted it is likely that the formation fluid such as oil or gas will be produced through such uncontacted portion. Such production will cause sand particles to be entrained and carried into the well bore. Thus it is seen that it is most important that the treating agent be properly placed within the formation.

Acordingly, it is an object of this invention to provide means whereby the treating agent is placed in the portion of the formation adjacent the perforation in the casing through which fluid is to be produced. In a preferred embodiment means are provided whereby an annular portion of the well bore adjacent the formation to be treated is isolated. A perforating gun is lowered through the tubing string until it is adjacent the isolated area. The gun is then fired, the bullet penetrating the casing and into the formation. Means are provided whereby treating fluid can then be injected through the tubing and the isolated space so that such treating fluid passes through the perforation just made and on into the formation. This assures that the portion of the formation adjacent the perforation through which formation fluid, such as oil, is subsequently produced has been contacted by the treating agent. Thus, for example, if an unconsolidated formation is being treated by a bonding agent, the critical portion of the formation is bound together to prevent production of sand or other particulate matter. The perforating tool can be reloaded and the isolated area moved to a second or other locations in the well bore and the treatment repeated.

Various other objects and a better understanding of the invention can be had from the following description taken in conjunction with the drawings in which:

FIGURE 1 illustrates a preferred embodiment of the apparatus of this invention supported in a well bore without a perforating gun located therein;

FIGURE 2 illustrates a section along the line 22 of FIGURE 1;

FIGURE 3 illustrates a section along the line 33 of FIGURE 1;

FIGURE 4 illustrates the apparatus of FIGURE 1 in which a perforating gun has been positioned; and

FIGURE 5 illustrates a perforating gun useful in the device of FIGURE 1.

Attention is first directed toward FIGURE 1 which illustrates a casing 10 set in a borehole which penetrates an underground formation 12 which is to be treated. Positioned within casing 10 and adjacent that portion of formation 12 to be treated is a tubular member 14 which is enclosed at the lower end as by cap 13. Tubular member 14 is suspended from the surface by a tubular means or tubing string 11 to which tubing 14 is connected such as by threads 15. An annulus 16 is formed between casing 10 and the tubular members (including tubing string 11).

Spaced from and above cap 13 is a port 22 in the wall of tubular member 14. Surrounding tubular member 14 and especially in the vicinity of port 22 is a sleeve element 18. Sleeve element 18 together with tubular member 14 forms an annular space 30 therebetween which is in fluid communication with the annular space 16 between the tubing string and the casing. A pad 2%, surrounding port 22, supports sleeve 18 from tubular member 14. Pad 2% completely surrounds and seals ports 22 and 26 from communication with annular space 36. Member 20 has a port .14 and together with ports 22 of tubing member 14 and port 26 of the sleeve 18 form a port means or window communicating the interior of tubing member 14 with the space 33 between sleeve 18 and casing 11}. (It is through one of these windows that a perforating gun is fired.) Space 33 is isolated from the remaining part of annulus 16 by upper packer 32 and lower packer 34. These packers are preferably of a cup type which will expand outwardly and seal with the casing upon fluid pressure being injected through ports 22, 24, 26 into isolated space 33.

Means are provided establishing fluid communication from below packer 34 to above packer 32. In this regard, pads 2% do not go circumferentially around tubing member 14. As can be shown in FIGURE 2 there is space 39A between the pads so that there is free communication between annulus 16 below lower packer 34 and that part of the annulus 16 above packer 32. The portion of annular space 30 which is above pad 2th is in free fluid communication through passage 30A with that portion of such annular space 30 which is below pad 20. Annular space 30 and passage 30A together form a passage between that portion of annular space 16 above packer 32 and that portion of such annular space 16 below packer 34.

Means are provided so that fluid can be circulated down through the tubing and back up annulus 16 and annulus 30. This includes a port 46 which is provided in the wall of tubular member 14 near its lower end and below port 22. A pressure relief tube 40 having port 44 aligned with port 46 is provided in the lower end of tubular member 14. Pressure relief tube 40 has exterior longitudinal passageways 42. Mounted immediately above pressure relief tube 40 within tubular member 14 is a gun orienting device or sleeve 36 which is provided with gun guide slots 38. The thickness of the wall of orienting device 36 is less than the radial dimension of longitudinal slot 42 of pressure relief tube 40. Pressure relief tube 40 and perforating gun orientating device 36 can be securely fastened to the interior tubular member 14 by conventional means such as by welding.

Attention is now directed toward FIGURE which shows a conventional casing perforating gun 43 which has been modified to meet the requirements of this invention. Shown is a perforating gun having a directional k charge 60 which is oriented 90 from tubular orienting pegs 58. Pegs 58 are spaced below gun 6t) and are adapted to fit into guide slots 38 of gun orientating device 36. As shown in FIGURE 1, the lower end of slot 38 is a distance H below the ports 22. This is the same distance which orienting pegs 58 of the perforating gun is below the directional charge 60 as shown in FIGURE 5. As also shown in FIGURE 5, a sealing nipple 52 is fastened to the perforating gun at its lower end. This sealing nipple is provided with an upper sealing means 54 and a lower sealing means 56 which can for example be O-rings. The size of sealing nipple 52 is such that sealing members 54 and 56 provide a firm seal with. the interior of pressure relief tube 40 when inserted therein thus closing ports 44 and 46. Slot 42 of the pressure relief tube 40 causes equal pressure to be exerted on the upper and lower surfaces of the gun so that it can be easily withdrawn from the tubing.

Having described the main structural components of this device, attention will now be directed toward its operation. The device shown in FIGURE 1 is secured to the lower end of a string of tubing 11 and lowered into position such that the window of the tool is at the depth which is to be treated. When the tool is lowered into the well bore no fluid pressure is applied to the tubular string 11 and thus cup packers 32 and 34 are in a relaxed position and the tool moves easily down the well bore. When the window is adjacent the depth of the formation to be treated, the perforating gun is lowered by cable 59 in a conventional manner. Cable 56 also contains conductor lines for actuating the perforating gun. When the perforating gun is lowered down the interior of tubing string 11, at first it is not yet lowered to where it seats or seals within pressure relief tube 40. At this time, the desired treating agent is forced downward through tubular string 11 until essentially all the drilling mud or other well fluid is displaced from within the tubular string. This well fluid is displaced out primarily through ports 44 and 46 at the lower end of tubular member 14 and up annulus 15 through passages 30 and 36A.

At this time, perforating gun 48 is lowered so that sealing nipple 52 i in pressure relief tube 41 When orienting plug 58 of the perforating gun is in the lower end of orienting slot 38 of the orientating device 36, sealing nipple 52 is positioned such that seals 54 and 5s; prevent fluid from within the tool passing through ports 4. 4 and 46. The interior of tubing 14 is then in isolated communication with isolated space 33. When continued pumping of fluid to tubing string 11 causes build up of pressure in the tubing string, it is known that the sealing nipple is in the pressure relief tube and that the orienting nipple 58 is in an orienting slot 38. If there s no build up of pressure, and assuming no failure of the seals, it is known that the perforated gun is not seated. When there is a pressure build up, it is further known that directional charge 66 is oriented opposite one of the windows of the tool and is thus in position to be fired. The perforating gun, after proper seating, is then fired through the window of the tool causing a perforation 62 in the wall of casing 10 and into the formation 12. After the perforation has been made, treating fluid is continued to be pumped down drill string 11 through perforation 62 and into the formation. Suitable treating fluids for consolidating a formation are described in the above mentioned US. Patent 3,189,091. Such treating fluid causes the formation adjacent perforation 62 to become consolidated. Of course, this apparatus and method can be used for treating fluids other than those for consolidating a formation.

If it is desired to treat another interval of the formation at a different depth the device is moved vertically in the well bore to such new location. This can conveniently be done by releasing the pressure on the tubing string 11. which causes packers 32 and 34 to relax. They can then be moved fairly conveniently by movement of tubing string 11 in a conventional manner. The spent perforating gun is removed and a recharged perforating gun is lowered into the tubing string. Then the above described operation is repeated.

While only one preferred embodiment of the above invention has been described in detail, various modifications can be made thereto without departing from the scope of the invention. Therefore it is desired that the scope of the invention be defined only by the following claims.

We claim:

1. An apparatus for use with a perforating gun having a directional charge used to perforate a casing set in a. well bore which comprises:

a hollow member having a window therein and adapted to receive said gun;

upper annular sealing means above, and lower annular sealing means below said window and supported exterior of said hollow member for sealing engagement with said casing to form an isolated space between said sealing means;

a passageway establishing communication of space exterior of said hollow member below said lower sealing means and that space above said upper sealing means;

means within said hollow member for orienting the directional charge of said perforating gun with said window of said hollow member; and

means establishing fluid communicating between the interior of said hollow member and the exterior thereof below said lower sealing means, which means is closed by the lowering of said perforating gun into said hollow member.

2. An apparatus including: a perforating gun in which said perforating gun has a sealing nipple extension carrying an upper ring seal and a lower ring seal and a pair of diametrically opposite orienting plugs exterior of said gun, and a charge oriented 90 from said orienting plugs;

a tubular member having diametrically opposite ports spaced from its lower end and a pressure relief port spaced longitudinally between such ports and the lower end of said tubular member, said tubular member extending to the surface;

cap means enclosing the lower end of said tubular member;

an orienting sleeve mounted in said tubular member below said ports and above said relief port and having diametrically opposite slots for receiving said orienting plugs of said perforating gun, said slots being oriented 90 from said ports of said tubular member, the longitudinal distance from the lower end of said slot to the center of said port means being the same as the longitudinal distance from said orienting plugs on said perforating gun to said shaped charge;

a pressure relief tube fixed within said tubular member below said orienting sleeve and having a port in the wall thereof aligned with the relief port of said tubular member, said pressure relief tube having a longitudinal passage in the well thereof, the interior diameter of said pressure relief tube being of a size to sealiugly receive said sealing cap of said perforating gun;

a sleeve surrounding said tubular member and extending above and below said ports and having ports aligned with the ports of said tubular member;

support pad means surrounding said ports of said tubular member and filling less than a full circumferential part of the annular space between said sleeve and said tubular member; and

an upper sealing means and a lower sealing means carried by said sleeve respectively above and below said window.

3. An apparatus for use with a tubing string and perforating gun having a directional charge and used to perforate a casing set in a well bore which comprises:

a hollow member having a window and adapted to be connected to a string of tubing;

annular sealing means supported by said hollow member for isolating a portion of the annulus between said hollow member and said casing, said isolated portion being in fluid communication through said window with said hollow member;

a passageway supported by said hollow member establishing fluid communication between the annulus above and below said isolated portion;

means within said hollow member for orienting the directional charge of said perforating gun with said window of said hollow member; and

port mean in the wall of said hollow member establishing fluid communication between the interior of said hollow member and the annulus between said hollow member and said casing and below said seating means, said port means being closed by said perforating gun when said gun is lowered into said hollow member.

4. A method of treating with a treating agent an underground formation behind a casing in which a tubular member is suspended which comprises:

(a) isolating a portion of the well bore adjacent the formation to he treated, said portion being in fluid communication with the interior of the tubular member;

(b) displacing well fluid from said tubular member through the lower end of said tubular member by injecting said treating agent through such tubular member;

(c) then closing said lower end of said tubular memher;

((1) after said displacing step, perforating said casing through said isolated portion while maintaining said isolated portion in fluid communication with the interior of the tubular member, said tubular member extending to the surface; and

(e) injecting said treating agent through said tubular member and isolated portion through said perforation into the formation to be treated.

5. A method as defined in claim 4 in which formation fluid is thereafter produced through said perforation.

References Cited UNITED STATES PATENTS CHARLES E. OCONNELL, Primary Examiner. IAN C. CALVERT, Assistant Examiner. 

